The movie begins with Paige Collins (Rachel McAdams) and her husband Leo (Channing Tatum) coming out of a movie theater. On their way home, when they stop at a stop sign, Paige unbuckles her seatbelt to lean over and kiss Leo. At that very moment, a truck rams their Saab 900 from behind and Paige crashes out through the windshield. Both of them are rushed to the emergency room, and as Leo, in a voice-over talks about how "moments of impact.. help in finding who we are" the movie cuts to how Paige and Leo first met. The scenes of how they courted, proposed and married are interwound with the present.When Paige regains her consciousness, she thinks Leo is her doctor, implying her loss of memory.